Start with the Tree View.
Set attributes to display on the left, title on the right.
Expand the application window as wide as your desktop, doesn't need to be maximized but you can do that too.
This looks as expected:

Now just go to List View.

It seems the title grid is only showing a fixed width for the backcolor, but the highlight for the selected task is correctly the width of the column.
That said, there is an anomaly when selecting a different task. The width of the selection highlight is inconsistent as the selection is changed. But this clears when the grid is repainted, like when the form is resized.

HTH
T